Pm932m-y Tram Off .003 Over 4"-y Gib Adjustment?

I watched the tramming part 1 video on the g704. I also used a spindle square to verify. I feel pretty confident the column and head are square. I will concentrate on cleaning up the mating surface. Hope it's not a nightmare. I knew I kept my shop crane for a reason :)
 
Dan_S said:
That's an understatement. Telling people to not use the ball on a dti is unforgivable.
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haha. I missed that. I remember there were some other somewhat odd things. Largely why I don't like the drill rod in the spindle is it introduces other possible errors into your measurement (collet run-out, more than one axis out of tram making erroneous readings while running a DTI up the length of a small diameter rod).

Cylindrical square on the table gives you a solid perpendicular surface to measure against as the head is raised and lowered, minimizing stack-up of errors.

Gburgswmich said:
I will concentrate on cleaning up the mating surface. Hope it's not a nightmare.
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Not that bad.

But cleanliness is everything. Treat it like a clean-room operation. Slightest bit of grit will put you further off than you started. Wipe the surfaces down with acetone when you think they are absolutely clean before you join them together.

But worth doing. It sucks when you flycut a surface, and every pass of the mill leaves a 0.003" groove where it meets up with the previous path.
 
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Yes its very common to need to shim the column on these types of mills to get them to be dead on. But as already mentioned, there are a lot of variables, but these guys are giving you good information.

It wont hurt to shim it, but also wont hurt to use it as is for a bit too just learning to mill. Its actually fairly easy to shim it. I did one for a local person here recently, on the same mill. Are you .003 Total over the whole sweep? Or .006 total with it being low in the front?

This one was about .003 Total over the whole table, and we used about .002 shim and it was dead on after that. But it varies on the amount all the time. The bolt torque moves it a bit too. It wont take long though, you'll get it I am sure.
 
So the .003 is the measured with s spindle square where the points of contact are 4" apart. The front of the head is closer to the table, so I'm assuming the front of the column will need to be shimmed. When I pull the left side of the spindle square down (contact point on the back side of the table) the square gets closer to dead on. That tells me the column needs to sit more upright.

I've milled on it a bit already, and am getting comfortable with it, but I want to get it square. I need to mill some dead flat bearing pockets in titanium SOON for a folding knife project and just don't want that as a variable of error.

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Ok, so when you turn the spindle 1/2 turn, its exactly the same that way too then right? (I apologize if you already said that, I just did not see it)

But yes if thats it, you would need to shim the front of the column. The one that is on 0 is towards the front of the machine right?

You'd notice it on a fly cutter, but probably not on an end mill. If your spindle is at .0015 high in the back and .0015 low in the front over 2" Each, and you have a 1/2" end mill in there, its a much much smaller difference. But it is better to get it perfect, the closer it is the easier.
 
When I had this type of mill I also had to shim the column to get the tramming dead on. It's really not that hard to do, just tedious as the shim thickness you need under the column it not the same as the amount you are off when checking at the quill. My process was to loosen the bolts holding the column, don't remove them just loosen, and push on the head enough to slip the shim under the column. Then tighten the bolts and check tram. It took me several attempts with different shim thicknesses to get it within .001". Also, shimming one corner will throw off the alignment in other directions. I think I had shims under 3 of the 4 corners with all 3 being different thicknesses.
 
This is exactly what I plan to do when I return from vacation. I was going to use compressed air to clean the mating surface while lifting the head and column with my shop crane. I'm going to be doing this myself so I figured I can loosen the bolts enough to create a gap when I lift the head and column. Clean the mating surface then shim and tram and repeat shimming as needed. Thanks for the post!

sanddan said:
When I had this type of mill I also had to shim the column to get the tramming dead on. It's really not that hard to do, just tedious as the shim thickness you need under the column it not the same as the amount you are off when checking at the quill. My process was to loosen the bolts holding the column, don't remove them just loosen, and push on the head enough to slip the shim under the column. Then tighten the bolts and check tram. It took me several attempts with different shim thicknesses to get it within .001". Also, shimming one corner will throw off the alignment in other directions. I think I had shims under 3 of the 4 corners with all 3 being different thicknesses.
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I'll check this when I return from vacation. Appreciate your help with this.

qualitymachinetools said:
Ok, so when you turn the spindle 1/2 turn, its exactly the same that way too then right? (I apologize if you already said that, I just did not see it)

But yes if thats it, you would need to shim the front of the column. The one that is on 0 is towards the front of the machine right?

You'd notice it on a fly cutter, but probably not on an end mill. If your spindle is at .0015 high in the back and .0015 low in the front over 2" Each, and you have a 1/2" end mill in there, its a much much smaller difference. But it is better to get it perfect, the closer it is the easier.
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So I'm back getting ready to set this up so I can lift the head and column to insert shims. Anybody with experience recommend me doing anything different than when first assembling the unit? I'm going to move the gear head to the very bottom of the column because my ceiling and this crane have clearance that forces me to do so. I'm putting a strap under the pivot of the gear head and lifting the strap with my shop crane from that point. I'm not going to fully remove the column bolts, only enough to get some clearance between the column and base. Because of the weight of the head, my concern is where I've got the gear head supported. Any recommendations? I'll take a pic and post....
 
Pics attached. This is how I installed the base column head onto the blue base when I first got it without too much of an issue. Since the base is not going to be connected here, is there anything else I should worry about here? I'm not lifting it completely off, just trying to get some clearance for shimming.
I'm a complete novice guys, so I know you guys see things that I don't because you've experienced the good bad and ugly. I don't want to ruin a 3k plus mill here :)

image.jpeg image.jpeg image.jpeg
 
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